scholarly journals Stressed deformable reflector design and pneumatic membrane antenna for cryogenic thermal vacuum chamber testing

Author(s):  
Marcos A. Esparza ◽  
Heejoo Choi ◽  
Hyukmo Kang ◽  
Christian d'Aubigny ◽  
Amarjiit Pandde ◽  
...  
2020 ◽  
pp. 61-66
Author(s):  
Вячеслав Владимирович Донченко ◽  
Игорь Федорович Кравченко

The main gas-dynamic parameters are considered for studying of the absence of flutter wide-chord fan of aircraft engine. The experimental-rated method is proposed to confirm the absence of flutter on the fan in the entire operating range of the aircraft engine. The method is based on experience in the design and development of aircraft engine fans. The method proposes the limitations of the study area of operation of a wide-chord of the aircraft engine fan. The method shows the boundaries of the possible operation of a wide-chord of the aircraft engine fan, taking into account the limitations of the studied range for the research and development of the testing. The aircraft flight parameters were processed with the control of the absence of flutter using pressure pulsation gauges. The results of processing the studied flight parameters are generalized and systematized. A technique for graphically depicting of the main controlled parameters of the method in a two-dimensional and three-dimensional setting is shown, indicating the boundaries of the possible range of operation, the wide-chord fan of the aircraft engine under study, taking into account the reserves of pressure and temperature. To verify the method, the test points of the fan are graphically showed in a thermal vacuum chamber of a similar sized fan of an aircraft engine, which, as the figures show, lie near the boundaries proposed in the method. It is proposed to use the studied points with a proven absence of flutter for verification of computational models using software systems and methods, for calculating the absence of flutter, taking into account the limits of possible operation defined in the method. The proposed boundaries of the studied ranges will significantly reduce the list of tests at the flying laboratory and the number of design points, which will allow us to make the best option for checking the absence of self-oscillations of the aircraft engine fan by the experimental-rated method in Ukraine without using a thermal pressure vacuum chamber and flying in hot and cold conditions.


Author(s):  
Анатолий Курочкин ◽  
Anatoli Kurochkin

The purpose of the research is theoretical substantiation of the influence of the thermal vacuum effect for the volume consumption of raw materials in the extruder with vacuum chamber. Theoretical studies of the working process of single screw extruders allowed us to obtain analytical expressions, which can be used to determine the volume flow rate of extruded raw materials serial machine. For extruders using thermal vacuum effect in their work, this theory does not allow to obtain acceptable results, since it does not take into account the fact that the technical solution implemented in the experimental extruder, compared with the serial machine allows to increase the coefficient of explosion of the extrudate in 1,5...2 times. In turn, this significantly affects the volume performance of the extruder and does not allow to determine with the necessary accuracy the structural and technological parameters of the vacuum chamber and its sluice gate. In this regard, in the carried out researches, on the basis of the equation of balance of mass of the processed raw materials which is in a path of the extruder and its vacuum chamber, the coefficient consid-ering influence of thermal vacuum effect on volume consumption of raw materials in the experimental extruder is theoretically proved, and also communication of this coefficient with other significant parameters of process of extrusion is established. The obtained results can be useful for further theoretical studies of extruders with thermal vacuum principle of operation and allow to calculate by analytical methods the main parameters of the vacuum chamber of machines performing thermoplastic extrusion of vegetable raw mate-rials.


2015 ◽  
Vol 43 (11) ◽  
pp. 1008-1015
Author(s):  
Heejun Seo ◽  
Hyokjin Cho ◽  
Sungwook Park ◽  
Gueewon Moon ◽  
Hwanil Huh

2021 ◽  
Vol 13 (7) ◽  
pp. 318-323
Author(s):  
Gennady Mishin ◽  
Nikolay Lelushkin ◽  
Andrey Basov ◽  
Gennady Fedoruk ◽  
Alexander Myakochin ◽  
...  

2005 ◽  
Vol 48 (1) ◽  
pp. 127-137
Author(s):  
Younggy Shin ◽  
Seok-Weon Choi ◽  
Guee-Won Moon ◽  
Hee-Jun Seo ◽  
Sang-Hoon Lee ◽  
...  

A thermal vacuum chamber is used to simulate thermal environments of a test satellite in orbits where daily temperature variations range from 80 K to above 400 K. The test facility is complex and consists of expensive parts. Modification of control software is discouraged as the modification may cause unexpected system failure. This paper describes a study that develops a real-time dynamics model of the thermal vacuum chamber that can be used to create control algorithms and simulate electrical inputs and outputs for interface with a programmable logic controller (PLC). The dynamics model is represented by simulation software and exported to a target PC in the Microsoft® Disk Operating System (DOS) mode to exploit the real-time kernel of the DOS software. The model is executed in real-time and communicates with a microprocessor-based input/output (I/O) board via a serial port to emulate electrical inputs and outputs. The target process to model is the gaseous nitrogen (GN2) mode in which GN2 circulates in a closed loop through thermal shrouds encompassing a test object. A blower boosts the GN2. Injected liquid nitrogen (LN2) and an electric heater control the set temperature of the GN2. The realized simulator dynamics are quite similar to those of the thermal vacuum chamber and serve as an appropriate system to verify the control performance of a programmed PLC.


2001 ◽  
Author(s):  
A. K. Ray ◽  
Dinesh Kumar ◽  
P. N. Rajendran ◽  
Usha D. Shastri ◽  
A. Atchamamba ◽  
...  

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